Thursday 31 December 2020

Beavers in Britain. Estate beavers in the 19th and 20th centuries

Successful attempts to reintroduce the Eurasian Beaver to Britain are now well known. Fortunately, and despite opposition, the various releases both ‘legal’ and ‘illegal’ (how it can be illegal to release animals native to mainland Britain I have difficulty fathoming out) seem to be working. Beavers are said to have been extirpated in the 1500s by hunting for fur, meat and castoreum, a secretion formed apparently by the walls of the castor sac near the anus, which was used in perfumery and as a food flavouring.

Articles have reported historical accounts of beavers being kept on large estates, possibly with a view to their eventual wider release. Most articles report that the beavers involved were not the native Eurasian Beaver (Castor fiber) but the North American species, Castor canadensis. However, examination of original records indicated that this was not so in one of the introductions, the first I describe.

The 3rd Marquess of Bute, John Patrick Crichton-Stuart (1847-1900), acquired beavers for his estate Mount Stuart on Bute, an island in the Firth of Clyde thirty miles from where I am writing this article. He is said to have imported four beavers in 1874 to be kept enclosed in a small wood. Since animals in zoos and other collections never ‘die’ but are ‘lost’, ‘poor doers’ and the like, these beavers were ‘not succeeding’  A further seven were then obtained in 1875. Those animals bred but the total numbers at any one time seemed to vary with the person doing the reporting if not the counting; 12 to 28 seems to be the range. As I indicated, most second-hand reports of the beavers on Bute have stated that they were Castor canadensis. However, the excellent website of the Bute Museum website contains more accurate information: 

Beaver Castor fiber were introduced to Bute in 1874 by the 3rd Marquess of Bute, but the species had died out by 1890. They were at one time reported to be the North American Beaver Castor canadensis, but correspondence in the Bute Archives revealed that the Beavers came from Scandinavia [references to research by the late Dr Jack Gibson].

Another group of beavers was in the south of England and they were reported as Castor canadensis. An account (Beavers in Sussex!) was given by L.R. Brightwell* in Animal and Zoo Magazine in 1938. Sir Edmund Loder (1849-1920) the then owner of Leonardslee, an estate near Horsham in West Sussex, at one time kept coypu and capybaras as well as the beavers. Brightwell’s seems to be the most accurate account of the date of their acquisition—around 1897. However, a letter to Nature in 1897 stated they had been there since 1889--the date Loder bought Leonardslee from his in-laws. A letter to The Times in  2010 stated that according to an old magazine article the beavers had been obtained by Loder’s great-grandfather in the 1850s. However, that cannot be the case because Loder did not buy the estate until 1889. According to the website for Leonardslee Gardens, beavers were on the estate until 1947.

Brightwell visited Leonardslee, where he was shown around by a George Stoner†, and described the ‘beaver yard’:

This is a lake, a quarter-mile long by fifty yards wide, hemmed in by trees and an inconspicuous barrier of sheet iron planted a yard deep in the soil. Such trees that stand within the enclosure wear skirts of sheet iron, and the necessity of such safeguarding is at once apparent. The dead lie all around—sixty-foot pine, larch and beech, white as ivory, for not one particle of bark has the beaver left upon them.

An early disaster came with flooding after a storm. The beavers swam over the barrier and reached the sea, thirteen miles down stream. There some fishermen in a boat hit the strange animals over the head and carried the corpses ashore in order to find out what they were.

A heavy iron grid spanned the stream from the lake. Every night the beavers attempted to build a dam at that point and every morning the estate worker with the job of looking after the beavers had the job of undoing their labours in order to prevent flooding. 

As well as beavers, both the Marquess of Bute and Sir Edmund Loder, acquired wallabies for their estates; those at Leonardslee are still there. The ones on Bute were released into the wild but I do not know how long they survived there.

For some time it seems the two species of beaver, North American and Eurasian were regarded as one. But they are ‘good’, true biological species, with different numbers of chromosomes. Attempts at hybridisation have failed to produce live young and where introduced C. canadensis meet C. fiber in Europe there has been no breeding between the two.

Brightwell remarked in discussing the tail of the beaver its use to generate an alarm:

Used as an alarm gun, it can strike the water with a force like a pistol shot…

That sound, which made me jump, was my first introduction to Castor canadensis. In 1973 and up very early because I couldn’t sleep on with 5-hour jet lag I wandered around the campus of Colby (now Colby-Sawyer) College in New London, New Hampshire, just after dawn. I stopped to look at chipmunks in the woods and as I passed the pond, the ‘force like a pistol shot’ hit my ears. I turned and there was a beaver. I watched the beavers there for several mornings that week and again when I was there later in the 1970s for Gordon Conferences; I was even able to show Americans their first beaver. However, by the 1980s I did not see any and the latest view on Google Earth shows the pond largely hemmed in by a new car park.

*Leonard Robert Brightwell (1889-1962) was a well-known and prolific author and illustrator. He had strong academic zoological connexions since he illustrated The Science of Life for the authors, H.G. Wells, Julian Huxley and G.P. Wells.

†I find George Allen Stoner (1869-1964) living in Horsham, three miles from Leonardslee, described as an ‘estate worker’ in the 1939 Register.

Tuesday 29 December 2020

Rain Stimulates Many Frogs to Breed. But HOW does it work?

Smilisca baudinii from Central America

In my last post here I remarked on the lack of knowledge of how the onset of seasonal rain induces breeding in a number of tropical birds. We know why that happens: the onset of rain presages the explosion of insect life on which young birds are fed but we do not know how that stimulus works.

Amphibians also breed in response to rain and some of them ought to provide an opportunity to discover what it is about rain that signals to the brain and sets in train the neuro-hormonal events that lead to breeding behaviour, egg production and fertilization.

I should make a distinction here between a physiological state of readiness to breed and the actual trigger that sends a signal loud and clear to ‘go’ such that in a matter of hours eggs have been laid and fertilized. It is this latter effect of rainfall I am discussing.

Many tropical frogs can and do breed throughout the year but only do so after rain. Herpetologists make use of this phenomenon to induce breeding in captivity. All sorts of devices have been rigged in the past to mimic the whole manifestation of a tropical downpour: simulated rain; tape recordings of heavy rain and thunder; setting off the simulated shower during a period of decreasing barometric pressure etc. Sometimes such manipulations work; sometimes they do not. When they do work though the results are spectacular; within hours there are masses of frogspawn.

Such set ups in captivity ought to enable the identification of what it is about rain that is important and to determine the senses that are being activated to pass on that signal to the brain. Thirty-five years after I was either breeding or attempting to breed treefrogs from central and northern South America, the use of a ‘rain chamber’ is established practice for some species, like the Red-eyed Tree Frog (Agalychnis callidryas). At this stage I should point out that a rain chamber is a vivarium arranged with a pump to recirculate water through a spray head such that ‘rain’ falls onto the plants and inhabitants below. It should, therefore, be possible to devise experiments to test the factors that might be important. For example, there have been suggestions that a sharp rise in humidity is a sufficient stimulus - easily tested by having a netting divider across the vivarium with frogs but not ‘rain’ on both sides; sealing the vivarium would enable changes in barometric pressure to be tested.

Red-eyed Treefrog from Central America

The outcome of such experiments might have a bearing on the old problem of how frogs and toads find their way to ponds in spring. A famous but now largely forgotten British scientist, Ronald Maxwell Savage (1900-1985) whose ‘professional’ hobby was studying the Common Frog, Rana temporaria, obtained some evidence that frogs can smell the algae growing in fresh water and thus move towards the source of the aroma. Could chemical sensing be involved in tropical frogs? Do they respond more reliably to recirculated aged vivarium water or to fresh rain water at the same temperature? How important is change in temperature? The possibilities seem endless but some pretty simple experiments would I am sure soon uncover which factors could be discounted at least in one species. We do not, of course, know whether the key factor about rain that stimulates breeding is the same in tropical tree frogs as in, say, a desert frog in Africa or Australia.

I was not able to take my breeding of species thought to be susceptible to tropical rain very far for the simple reason that other species I had, particularly dendrobatid or poison-dart frogs, were breeding so well that rearing their young was taking all my spare time. However, one species that sometimes did and sometimes did not respond to an artificial tropical storm was Smilisca baudinii, which has a number of common names including Mexican Treefrog and Masked Treefrog. One spawning by several females goes a long way and I raised a hundred or so past metamorphosis to a size where they could be passed on to others. With those which did not breed after an artificial downpour, an injection of human chorionic gonadotrophin (i.e. as in the human pregnancy test using Xenopus) resulted in fertilized eggs the next day. In other words the frogs had been ready to breed but my ‘rain’ had not been a sufficient or only stimulus.

Given the importance of rain in stimulating breeding in some amphibians as well as in some birds and other organisms, surely it is time we had experimental evidence on what it is doing and how it works.

Smilisca baudinii - captive-bred juvenile

Wednesday 23 December 2020

Rain and seasonal breeding. An unsolved problem in physiology

Red-billed Quelea - male in breeding plumage
Bernard DUPONT from FRANCE, CC BY-SA 2.0
via Wikimedia Commons


The origins of this story—and its unanswered questions—go back to the 1930s. J.R. Baker (1900-1984) was working at Oxford in the 1920s on the control of sperm formation in crickets when he went on the first of several expeditions to the New Hebrides. There, amongst other observations, on the large proportion of intersex domestic pigs, for example, he began to ask the question of what controlled the seasonality of reproduction of birds and mammals—and plants—in the tropics where there may be little or no variation in the environment during the year. He therefore planned another expedition to Espiritu Santo, the largest island of the New Hebrides, now Vanuatu. To continue the work after other members of the expedition had to return to Oxford, he took Tom Harrisson and, in Sydney, recruited ‘Jock’ Marshall (1911-1967). Other members of the expedition were his first wife, Inezita*, his sister Geraldine and Terence F. Bird (about whom I have no further information).

I will not dwell on the relationship between Baker and Marshall here. It is well described in the notes edited by Marshall’s late widow, Jane, here. In short, it began very well but in later years deteriorated badly. Nevertheless it was Baker and Marshall whose names became associated with factors controlling seasonal breeding in the tropics and of putting the questions in an evolutionary framework.

At first glance Baker and Marshall made an unlikely combination. Indeed, I knew people who worked in Oxford being surprised that Baker, the quintessential don, had ever ventured to the tropics or had qualified for a pilot’s licence. But he was the great-nephew of Sir Samuel Baker, the explorer of the Nile and Central Africa. Marshall, only later to obtain a degree at Sydney and an Oxford D. Phil. with Baker was a self-confessed larrikin, still sorting himself out after shooting off his arm in an accident but helping at the museum in Sydney and going on long birding trips to various parts of Australia. They were, along with Mrs Baker, Terence Bird and Harrisson, as tough as old boots. And they needed to be for the conditions encountered on Espiritu Santo were rough. This is how Jane Marshall describes just part of it:

There is constant talk in both their diaries [Marshall and Harrisson] of each others sores and fevers, dysentery and leprosy among the natives, malaria and one of the government men with blackwater fever for the third time. Jock talked of jagged coral disguised in foliage always ready to gouge a new wound, blowflies that deposited maggots on their blankets which then entered their open flesh, mosquitos, ants, spiders, cockroaches so numerous they scuttled round their feet nibbling at toe-nails while they were eating; 'they flew from wall to wall, gradually reducing calendars, photographs and record papers to flimsy ribbons; they ate holes in the bellows of my camera and shaved the titles from our books.' It was no tropic idyll; a body-wearing, tearing climate; 'each day at meal times Tom and I sat with our scarred legs in kerosene buckets of lysol and hot water - and we did much of our work in the kerosene tins each evening closely examining the lesions and jealously regarding each other's progress.' 

The expedition made detailed meteorological records as well as studying the reproductive organs of a number of animals and plants 'in an endeavour to determine the existence, periodicity and proximate causes of breeding seasons in one of the most uniform climates in the world.'

Baker drew together his survey of breeding seasons, including data from Espiritu Santo, in a chapter, The Evolution of Breeding Seasons, for a book to celebrate the 70th birthday of E.S. Goodrich published in 1938. On the wet tropics he wrote:

Occasional species may breed all the year round in certain places…but the general rule is for birds to have breeding seasons. The Oxford University Expedition to the New Hebrides…was struck by the seasonal behaviour of organisms in a little-changing climate. The climax was presented by the insectivorous bat, Miniopterus australis, the adult females of which all become pregnant once a year about the beginning of September, despite the constancy of climate and the fact that they hang all day in a dark and almost thermostatic cave.

Although the results of the expedition demonstrated seasonality of breeding in the wet tropics, ‘Baker and his colleagues were unable to show in the New Hebrides what factor or factors determined its onset, e.g. food supplies for the offspring, or more direct environmental factors such as rainfall, day length, light, etc.’

To a great extent the work of Baker and Marshall on what happens in the tropics was overshadowed by research, begun by William Rowan (1891-1957) in Canada, which showed that seasonal change in daylength is the major factor controlling the onset of breeding in organisms that live nearer the poles. Not only was that phenomenon demonstrated but the neuro-hormonal pathways that control the seasonal growth and activity of the reproductive organs by that route could be, and were, worked out. There have also been suggestions that even relatively close to the equator daylength is actually important in some birds. At latitudes of up to 10° the variation throughout the year is less than 1 hour of daylight per day.

Baker largely moved on to cytology and its techniques, a number of which he had applied to the reproductive organs. The torch for studying the factors controlling seasonal breeding in birds in the tropics was carried by Marshall until his death in 1967. His general thesis was summed up by the late Brian Lofts in Marshall’s obituary:

He strongly believed that the seasonal reproductive cycles of most birds were based on an autonomous cycle synchronized by a spectrum of environmental stimuli. These he classified into either accelerators or inhibitors. He always stressed that there was no single universal environmental regulator and that different species had evolved a response to different environmental stimuli.

What those environmental stimuli are and how they work bring me to the reason for writing this article.


In his 1938 chapter Baker, after scouring the literature of naturalists, described a whole range of environments in which the onset of rain after a dry season, or, in some cases longer drought, was associated with the onset of breeding in birds, amphibians and reptiles. Many of these observations are now of course well known. For example:

The tendency of tropical African birds to breed whenever the rains start has been remarked by several naturalists, and it has been pointed out that those species which breed in the spring in the subtropical parts do so in the tropical regions whenever the rainy season happens to be.

It was Marshall who demonstrated experimentally ‘the importance of rainfall as a breeding “timer” in an equatorial species’. That species is Quelea quelea, the Red-billed Weaver or Dioch, the most numerous non-domesticated species of bird on earth. I have never seen a large flock of the size justifying the bird’s description as ‘Africa’s flying locust’ because of its devastating effect on seed crops. We have however, seen impressively large flocks flying to roost before dusk against the backdrop of spray clouds from the Victoria Falls, from the verandah of the eponymous hotel on the Zimbabwean side of the Zambezi. And yes, a glass was raised to Jock Marshall; indeed some of the flocks were seen through the bottom of a glass.

However, despite a continuing appearance of paper after paper discussing the effects of rainfall on the onset of breeding of birds and how that stimulus might be more or less important than, say, changes in temperature or some other environmental factor, nobody so far as I am aware, answered the question of how rainfall brings about the hormonal stimulus to the reproductive system. Baker signalled the importance of the mechanism or mechanisms involved noting:

The receptor whose stimulation causes certain animals to breed when it rains is unknown, nor is it clear whether the stimulant is the rain itself or the small saturation deficit of the atmosphere or the existence of ponds or floods. It has been suggested in the Cape Verde Islands it is the green vegetation resulting from the rain, rather than the rain itself…

All sorts of possibilities of what it is about rain that is physiologically important. Sight, smell (of wet earth for example), touch, atmospheric pressure, change in temperature…and so on The list of possibles seems endless. But it cannot be beyond the wit of man to devise experiments to find out. Even more observational studies that produce associations will not suffice; experiments are needed. 

In this article, I have confined myself to mainly to birds since that was the main interest of Baker and Marshall. In a follow-up I will deal with amphibians since there is the possibility of a more convenient experimental approach to determining how rainfall stimulates breeding.

There may, of course, not be a single mechanism by which rainfall stimulates breeding even within a species, let alone between different species. But, more than 80 years since Baker wrote his chapter, it does seem remarkable that we still do not know the answer.

*Her affair with Richard Crossman, (1907-74), the future Labour MP and Minister caused a great scandal in Oxford. He is referred to tangentially in Baker’s Biographical Memoir: ‘Inezita Hilda having been captivated by the charm of the Vice-Warden of New College’. They married in 1937; she died in 1952.

Baker JR. 1938. The evolution of breeding systems. In, Evolution, edited by G.R. de Beer. Oxford: Clarendon Press.

Lofts, B. 1968. Professor Alan John Marshall, D.Sc., D. Phil., 1911-1967. Ibis 110, 206-207.

Willmer, E.N., Brunet, P.C.J. 1985. John Randal Baker. 23 October 1900-8 June 1984. Biographical Memoirs of Fellows of the Royal Society 31, 33-63

Sunday 20 December 2020

'Perilous Paradise'. Zoology in New Guinea in 1936. Mr Marshall and Miss Cheesman

The readers of the copy of Zoo (later called Animal & Zoo) Magazine—a joint venture between the Zoological Society of London and Odhams Press)—that landed on their doormats in August 1937 would have been fascinated by the accounts of travels in New Guinea by two writers whose articles appeared alongside one another. What neither article states is that the travellers, both of whom became legends in their own lifetime, actually met on location.

'Jock' Marshall

I have written before on the life of Alan John ‘Jock’ Marshall (1911-1967), the larger-than-life Australian zoologist. In 1936 he was in New Guinea scouting in order to build a proposal along with Tom Harrisson for an Oxford Exploration Club expedition. His efforts were in vain; he fell out with Harrisson and the expedition never happened, with permission to move out of heavily patrolled areas in the former German colony controlled under a mandate by the Australian government—the country was and still is a dangerous place—refused. He did, though, travel extensively in northern New Guinea, and he did publish a book describing the people and the birds-of-paradise he encountered. His memoirs, edited by his late second wife, Jane, are available online here. This is the account of his meeting a redoubtable and intrepid female collector and traveller.

At Aitape there was news. Jock exulted 'There's a woman in our midst!! - Oh la la la la - probably a wizard female anthropologist!! perhaps a travelling woman writer—in a cutter!—or maybe—‘ 

As soon as he heard she'd come from Hollandia he knew who she was—Evelyn Cheeseman [sic], the English entomologist. Herr Stuber had told him she was coming. She made the trip in a native outrigger canoe; not at all unusual for her. For years she had been wandering about in all parts of the tropic world seeking specimens for the British Museum. Jock was delighted—‘She is intrepid & indefatigable & is that strange, unusual & wholly attractive thing—a woman with brains & charm.' In that compliment there was the usual implication of male superiority, and it was typical of Jock's attitudes at the time—indeed, there was always an element of it in his thinking, however hard he tried to be fair; and he did. 

     He went along to talk with her. He hoped she might have useful information about the Dutch territory, but found much of her work had been done around Hollandia at 4000 feet and at a lake nearby. They discussed boats. They both needed to travel to Wewak to connect with the mail steamer. Waiting for the boat was a game of chance; there was no radio link with Wewak—only messengers. Predictably it became a week overdue. 'How perfectly bloody typical—position becoming serious—may have to walk or canoe, & in any case will have a female on my hands. Still, I guess she's the best female in the world to be in a "crisis" with. Some consolation.' It is just as well Evelyn Cheeseman was not a party to these strutting male thoughts; but he had a great respect for her. She was thirty years older than Jock, which added to his admiration for her resource and courage. 

     Finally a runner arrived—the boat would not be at Aitape perhaps for weeks. As they had suspected, they must make the hundred mile journey by native canoe. So the next day they left by the big island outrigger for which they had negotiated some days before. Out to sea they found themselves under huge square sails of strapped-together patches of fibre, the thirty-foot mast creaking and straining in the wind. The outrigger, a sharpened log a foot thick, swished through the waves as a steady breeze hurried the trader eastward. They stopped only to adjust cargo; they were also carrying the mail. They ate on the sand and took off again within an hour, afraid that rough weather might spring up and delay them disastrously. Jock could not afford to miss another ship. 

     All through that night and the next two they sailed on, watching the stars, talking and dozing: 'The outline of the canoe picked out by sparkles of phosphorus & each paddle breaks the water to a swirling flame.' In the day the sun was high, the sea glaring. They got sunburnt, wrote and talked in a desultory fashion, worried about being becalmed, and drank coconut juice from the cargo of nuts. They had to drive the crew to work ever harder because their calculations told them they would reach Wewak with only four hours to spare. 

     They arrived at midnight on the fourth day. It was no surprise to discover the mailboat for Sydney, due to leave at dawn, was not leaving until the following day.

Marshall returned Sydney in October 1936.

I cannot help but wonder how the 24-year old Marshall introduced himself to the 54-year old Miss Cheesman. Surely not, ‘Miss Cheesman I presume’.

Marshall photographed this Cuscus
which has been heavily retouched
by the printer

Lucy Evelyn Cheesman

Evelyn Cheesman’s life  (1881-1969) was as remarkable as that of Jock Marshall’s. She was appointed Assistant Curator of Insects at London Zoo in 1917; in 1920 became the first female Curator. She resigned in 1926 devoting the rest of her life collecting insects, plants, reptiles and amphibians for, or working as a volunteer at, the Natural History Museum in London. She received some funding from the museum but financed her many expeditions to the Pacific islands and New Guinea from her own funds, by collecting for other museums and income from writing.

Evelyn Cheesman
from here

Their experiences in New Guinea were put to use in the Second World War. Evelyn Cheesman wrote of the area and of the Japanese invasion for the Geographical Journal. In one paper she described with first-hand knowledge the activities of Japanese spies on the north coast of Dutch New Guinea in 1938. They posed as botanists complete with vasculum but the Dutch administrator got a local boy to follow them covertly. They took photographs of port installations and the like and also collected some plants which where stuffed into the vasculum before they boarded the ship to move on to the next port. The boy, sharp as a tack, watched which plants were collected and himself took samples back to base. They were all common species that could be collected anywhere in New Guinea. Her second paper, in 1943, was clearly written with the knowledge and collaboration of military intelligence. My guess is her detailed knowledge of New Guinea was being put to good use against the Japanese. She had, with her good knowledge of German, worked for the Admiralty on economic intelligence during the First World War.

Jock Marshall became the ‘One-Armed Warrior’. He persuaded the Australian military that despite having shot off his arm in an accident as a boy, he should fight in New Guinea. In January 1945 as part of the Aitape-Wewak Campaign Captain Marshall led ‘Jockforce’, ten-men strong plus local carriers, behind enemy lines on a reconnaissance patrol through his old stomping ground and in so doing killed and captured some Japanese while acquiring a nasty dose of amoebic dysentery. There is a wry irony in what was used to communicate with headquarters. Pigeons were parachuted into this future leading figure in the physiological ecology of birds. A history of the use of carrier pigeons by the Australian forces reads:

During February 1945 an important Infantry patrol known as Jock Force had been out of communication with 6th Australian Division for some days when 4 Pigeon Section was ordered to drop pigeons from aircraft to the patrol for the purpose of carrying vital reports back to Division Headquarters. Shortly afterwards six birds were successfully dropped by parachute to the patrol. Despite the fact that these pigeons had only previously been used on the coastal areas over distances up to 10 miles and high features in the Torricelli Mountains had to be negotiated, the first pigeon brought back a message a distance of 45 miles in 50 minutes after being fired on by the enemy on release. From information carried by these birds many successful air strikes were made and future operational moves were planned.

Captain Jock Marshall (2nd left) on 6 January 1945. Aitape
'Personnel of "Jock Force" 2/2nd Infantry Battalion preparing to
move out from the Australian and New Guinea Administration
Unit Headquarters at the start of their 40 day patrol over the
Torrocelli Ranges, through Yambe and along the Sepik River
behind enemy lines'
From here

Aitape. 8 January 1945
'Personnel of "Jock Force" moving off for Yakamul aboard a
3 Ton Truck'
From here

From the scientific point of view Jock Marshall did not waste his time in the army. Brian Lofts (1929-2015) who worked with Jock Marshall for many years at St Bartholomew’s Hospital Medical School in London wrote in Marshall’s obituary for The Ibis:

Characteristically, even during this period he carried out scientific observations on the jungle avifauna and, many years later at Bart's, presented me with material to study which he had collected in the army and preserved in gin!

Marshall AJ. 1938. The Men and Birds of Paradise. Journeys through Equatorial New Guinea. London: Heinemann.

Tuesday 15 December 2020

Statistics, repeatability and logic. Gaddum, Dale and one chicken

A story that used to be told in the coffee rooms concerned Sir John Gaddum FRS at a time when he was assistant to who was to be become Sir Henry Dale OM PRS, Director of the National Institute of Medical Research. Dale had a long interest in the hormones of the posterior pituitary.

The two mammalian hormones, vasopressin and oxytocin, had recently been partially (but not completely) separated from pituitary extract and Gaddum, appointed by Dale in 1927, had the job of comparing their effects on blood pressure. In contrast to mammals in which an injection of vasopressin causes and increase in blood pressure, hence the -pressin part of the name, Gaddum found in a chicken that vasopressin* caused a decrease in blood pressure. Thinking he ought to check the finding, he approached Dale for permission to buy another chicken or two.

Dale’s reply and point-blank refusal went along the lines of: Why on earth would you want another? Did you not do the experiment properly? Being assured by Gaddum that the experiment had been technically fine, Dale continued: If the result was observed and even if you had another dozen chickens in which you had the opposite result, you would still have to explain why you found a decrease in blood pressure in that chicken. So no, I cannot let you waste your time and the Medical Research Council’s money. No more chickens.

Had Dad's Army been on television on a still-to-be-launched television service I think we can envisage Dale adding, 'Stupid boy'.

This recording of blood pressure (shown then as now in mm of mercury)
before and after an intravenous injection of vasopressin in an
anaesthetised chicken was made on a smoked drum.
 From Gaddum's 1928 paper.

I suspect Gaddum, who became the expert on statistical treatment and design of bioassays, must have told the story himself to members of the Institute of Animal Physiology (now the Babraham Institute) when he was Director from 1958 until shortly before his death in 1965.

I shudder to think how many important findings are missed by the modern obsession with repeatability and statistical treatment of data before, during and after an experiment. If you cannot repeat a finding you have to be able find an explanation of why you cannot repeat it, and that explanation may itself be of biological significance. Perhaps that should be called the Dale-Gaddum rule?

Dale and Gaddum ca 1960
from here

*Vasopressin does not occur in birds. The avian version is arginine vasotocin

Gaddum JH. 1928. Some properties of the separated active principles of the pituitary (posterior lobe). Journal of Physiology 65, 434-440.

Sunday 6 December 2020

Doonfoot Lagoon, Ayrshire: Its history. Brackish or Fresh Water?

What has become known as Doonfoot Lagoon in Ayrshire has provided a great deal of excitement for birders and photographers. This year, as well as in 2017, a Spotted Crake (Porzana porzana), a scarce summer visitor to Britain from its wintering grounds in Africa was not only in residence but could easily be seen.

What most people visiting the locality do not realise is that the ‘lagoon’ has formed relatively recently in an area once inundated by the sea at high tide. Water flows into and out of the lagoon from the River Doon which enters the Firth of Clyde at this point on the coast. To illustrate how recent it is I have downloaded present and historic satellite views from Google Earth and brought them roughly to the same scale (judged by the length of the nearby car park). The photographs were of course taken at different states of the tide in the various years but at the start of the series (1999) the sea reached the sand dune in front of the car park. There was no lagoon at all. On the latest photograph available (2018) not only can the lagoon be seen virtually in its present state but also the presence of a now large and vegetated sand dune on its seaward side.

In the intermediate years, a shallow area filled with water, often containing seaweed or with seaweed round the edges (which rotted with that characteristic aroma) formed on occasion but was then sometimes washed away by the sea. That is what appears to be present in the 2005, 2007 and 2011 photographs. It was sometime between 2011 and 2016 that the lagoon in its present state formed, as the dune on the seaward size increased in extent.

test 1
Satellite Images from Google Earth

Flow into and out of the lagoon is now confined to passage over a shallow bar that forms a sandy bank of the River Doon. At high water, the level of water in the lagoon appears to be the same as that in the river. As the tide ebbs, the level of water in the lagoon falls.

At high tide, the water level in the 'lagoon' (left foreground) equals that in the River Doon (flowing right to left)

Having seen the various changes at Doonfoot over the past 42 years and the recent formation of the lagoon, I had always assumed the water in it would be brackish. Over the past couple of years  though I began to think that, with the changing vegetation and the fact that terrestrial birds like starlings can be seen bathing in it, the salinity may be low, not qualifying even for the term ‘brackish’.

I should say at this point that I do have some proprietary interest in marine birds and their existence on salt water, having written a monograph on salt glands in the 1970s and having worked for ten years on how those glands work to remove salt, ingested as part of their food or by drinking salt water, from the blood. Because salt glands need a lot of energy I often look at birds in estuaries and look for clues as to whether the salt glands are working at the time, drips off the end of the beak, swelling over the salt glands in the head, for example.

Having been fooled before about the salinity of a pool at the top of a sandy beach in Hong Kong which contained tadpoles (it was fresh water), I decided to measure the salinity of the lagoon. Having had, for 40 years, access to laboratory equipment that would have provided the answer I rather grudgingly had to buy the cheapest but best tool to do the job—a refractometer. Amazon soon had one at my door which on checking the calibration proved to have been set spot on at the factory somewhere in China.

To cut to the chase, the salinity of the lagoon was indistinguishable from Ayrshire tap water; no sign of any degree of saltiness. I also took sample from the wash over the entrance to the lagoon and from the river to the seaward side of the lagoon. Again, they were all fresh water. By contrast, at the point where on the day waves were starting to break on the shore, the salinity was 2%* (Atlantic sea water is around 3.5%). These samples were taken at high tide on 10 September. At low tide on 12 November, the lagoon and its outflow was fresh. I then walked to the furthest point of the beach I could reach seaward to the south of the lagoon to take a water sample there. It was full-strength (3.5%) sea water.

Salinity measurements mapped to GPS co-ordinates on Google Earth

What seems to be happening is that the lagoon fills from and empties into the river at a point which at high tide is above the mixing zone of fresh water flowing down the Doon and sea water in the Firth. With the incoming tide the level of the river rises not as a result of a movement of salt water but of a backup of river water. Therefore, the lagoon is partially flushed with fresh water twice a day, which would account for the fact there is no residual salt. I took the samples at times when rainfall and therefore flow down the Doon was and had been high. I am interested to see what happens on a high storm-driven tide at a time when flow down the river is relatively low. Will the mixing point be further upstream and will the lagoon turn brackish as a result? If it does, then my guess is that the salt water would soon be washed out when things returned to what appears to be the present normal state.

The appearance of bulrushes or reedmace (Typha latifolia) also gives some indication of salinity. Although it will tolerate slightly brackish water, there is in the north American populations tested a major reduction in the length of the leaves when the salinity is raised from 0 to 0.4%.

The mixing of water from rivers entering the sea is complicated. Satellite photographs show that the river water still forms a discrete moving mass well into the Firth (and birds like swans are often lined up along the flow, feeding on whatever is being brought down). Depending on the temperature difference there may be a layering of less dense fresh water over the salt. I must at this point thank Robin Turner in a discussion on Ayrshire Birding for pointing out a useful website on what happens when rivers meets the sea.

This image from Google Earth shows the channel into the Firth of Clyde made by the River Doon

The formation of the ‘lagoon’ raises several questions:

  • Will the ‘lagoon’ remain or will it and the sand dune which protects it be washed out in the future with the coast returning to the state it was in 1999?
  • Has a freshwater ‘lagoon’ formed previously and then been washed out?
  • Is its presence part of the phenomenon of rebound from the ice ages (with falling sea levels) in northern Britain?
  • Is it increasing in length?
  • Are changes at the mouth of the Doon connected with the state of the numerous weirs and/or flow from the dammed Loch Doon?

I find it difficult to know what to call the Doonfoot ‘lagoon’. By some definitions, since it is not sea water, it cannot be called a lagoon. Perhaps ‘inlet’ would be more appropriate.

Finally, a biological question: how do birds like the Spotted Crake—which fly by night—find a suitable habitat in which to land and live? Do they use the sense of smell to detect plants or rotting fresh water vegetation, for example? Whatever the mechanism, there is no doubt that Water Rails (Rallus aquaticus), as well as the occasional Spotted Crake, soon found this entirely new location and moved in.


*I am using percentage (%) to express salinity. Geographers and industry usually uses parts per thousand (0/00) while physiologists work in molarity or molality. Percentage is most easily understood by all.

Peaker M, Linzell JL. 1975. Salt Glands in Birds and Reptiles. Cambridge: Cambridge University Press


The bed of bulrushes at the western (distal) end

Friday 27 November 2020

Selecting Good Students: Sherrington’s Frog Test

The second paragraph of Sir Vincent Wigglesworth’s (1899-1994) biographical memoir for the Royal Society reads:

His father was imaginative, encouraging his children to collect material for demonstrations such as the microscopic life in a drop of pond water or the circulating corpuscles in the web of a frogs foot. Many years later, V.B.W. mentioned the fascination of the frog preparation to Sir Charles Sherrington, then living in Master’s Lodge at Caius. He said he used it as the ‘acid test’ for identifying research students. Less dedicated students glanced down the microscope and passed on, but future ‘physiologists’ were unable to tear themselves away from the view of blood cells bustling along capillaries. 

I am delighted to report that I unknowingly passed Sherrington’s test too. I was given what was little more than a toy microscope around the age of fifteen and was transfixed first by watching the blood circulation in a tadpole’s tail and then a frog’s web.

An old school friend dug this out of his loft
before moving house earlier this year. We had
identical microscopes made by J & L Randall
under the trading name of SEL (Signalling
Equipment Ltd). The magnification was fixed
at 100x. My father made a case for both of us
but mine along with the microscope have long gone

Sir Charles Sherrington (1857-1942)
(Wellcome Images)

I looked for a good demonstration on YouTube or in commercial libraries; they can be found with a simple Google search. However, I was disappointed since the magnification used is sometimes too great and the ability to rack the focus up and down is missing. The extraordinary contortions of the red cells are evident as well as some of the jostling as vessels branch. But there is nothing like the real experience.

In the Wellcome Library’s collection I did find an old gem, made in 1923, shot in black-and-white. One of the photographers was August Krogh (1974-1949), the Nobel Laureate famous for his work on control of capillary circulation. 

Liddell EGT. 1952. Charles Scott Sherrington 1857-1952. Biographical Memoirs of Fellows of the Royal Society 8,  241-270

Locke M. 1996. Sir Vincent Brian Wigglesworth, C. B. E., 17 April 1899 - 12 February 1994. Biographical Memoirs of Fellows of the Royal Society 42, 541-553.

Sunday 22 November 2020

Herpetology in Britain: The Trio of Medical Men—Smith, Bellairs and Frazer

A fact, noted in a biography of one of them, is that all three authors of the editions of
The British Amphibians & Reptiles and its successor in the Collins New Naturalist Series published from 1951 onwards were medically qualified

There was very little academic interest in reptiles and amphibians in Britain. Yes, of course, there were the famous herpetologists at the Natural History Museum in London but their interests in the 20th century were taxonomy and systematics, again not of burning interest to the biologists of the day. And there were those using amphibians to study developmental processes and basic physiology for which the frog is ideal. Comparative studies also included reptiles and amphibians but generally only en passant. Famous British palaeontologists devoted much of their lives to reptiles and amphibians but of the physiology, behaviour and ecology of living forms there was virtually nothing. Thus in a directory of research in British universities in 1960-61, only three individual entries refer to research in herpetology (other than a very specific interest in, for example, the structure of a particular organ) or developmental biology. They were: Angus Bellairs at St Mary’s Hospital (reptilian anatomy), London, Eric T.B. Francis in Sheffield (reptilian physiology) and C.L. Smith in Liverpool (amphibian physiology).

I think there are two reasons why research on reptiles and amphibians in Britain was not a topic of interest in the universities. The first is obviously the sparsity of species. The second is that research solely on one group of vertebrates, as opposed to a wider comparative approach, might have seen to have been unimportant in that there were unlikely to be discoveries made of wide biological significance. Whatever the reasons, it is not surprising that the major advances in reptilian ecological physiology, particularly thermoregulation, were made in the U.S.A. in the middle years of the 20th century where there is a rich herpetofauna and considerable academic interest.

The man who pulled all the information of British amphibians and reptiles together, including that gathered by very gifted amateur naturalists in Britain as well as in continental Europe, was Malcolm Arthur Smith (1875-1958). He was keen on amphibians and reptiles as a child but knew the only way he could pursue that activity was by earning a living as a doctor. After qualifying at Charing Cross Hospital and practice in London he went off to Bangkok as medical officer to the British Legation. That job was then extended to physician to the royal household. During his time in Siam, now Thailand, he was active in natural history, collecting specimens and writing accounts of the herpetofauna of south-east Asia. In 1925 at the age of 50 he retired to London where he was given space at the Natural History Museum. From there until his death he published extensively particularly on the reptiles of south and south-east Asia. From its founding in 1947, Smith was president of the British Herpetological Society. It was when he was over 70 that he turned to the British herpetofauna again, with the first edition of the New Naturalist volume appearing in 1951.

Angus d’Albini Bellairs (1918-1990) was co-editor of the fifth edition onwards of Smith’s New Naturalist book. Keen in reptiles as a boy he included zoology in his pre-clinical medical course at Cambridge. After qualifying in medicine from University College Hospital, London, he served in the Royal Army Medical Corps in north Africa, Italy and Burma, collecting reptiles throughout and sending preserved specimens back to London. After the war he published two papers with Malcolm Smith. One, on the head gland of snakes, read to the Linnean Society in 1944, must have been the result of work done while he was a medical student or while he was still in the army; the material was mainly that collected by Smith in Siam before 1925. The second paper, published in 1953, was on the egg-tooth of snakes. By that time he had been appointed lecturer in the anatomy department at the London Hospital medical school by James Dixon Boyd (1907-1969) who had been one oh his lecturers at Cambridge and who had stored Bellairs’s specimens from overseas. They published a paper together. Boyd took Bellairs back to Cambridge with him in 1951 but Bellairs preferred London and faced with a heavy teaching load in human anatomy he moved to St Mary’s Hospital medical school in 1953. Many anatomy departments had interests in comparative anatomy and Bellairs became the torchbearer for academic herpetology in Britain, albeit with an emphasis on anatomy, since he was self-avowedly ignorant of the advances in physiology, behaviour and ecology.

Joining Bellairs as co-editor of Smith’s book and then the sole author of the follow-up volume in the same series, Reptiles and Amphibians in Britain, Deryk Frazer had a somewhat similar history but this time came from medicine to become a professional working in conservation via physiology. John Francis Deryk Frazer (1916-2008) was born of a professor of anatomy at St Mary’s, John Ernest Sullivan Frazer (1870-1946). Switching from maths to physiology at Oxford he qualified in medicine in 1942. For the rest of the war he served as a surgeon in the Royal Navy on the new frigate HMS Helford in the Indian and Pacific Oceans. He then became Assistant Lecturer in Physiology at St Mary’s, a famous department headed by Arthur St George Joseph McCarthy Huggett FRS (1897-1968) engaged in fetal physiology and growth. Frazer worked on factors affecting fertility in the rat which formed the basis of his London PhD thesis awarded in 1953 (a mistake in a biography mistakenly attributed his PhD to work on toad movements). From St Mary’s he moved to the department of physiology at Charing Cross Hospital medical school where his main work was again on fetal growth and survival in collaboration with Huggett. However in 1959 he ditched academia to join the Nature Conservancy where he was a member of the British delegation at the first CITES convention. He did, however, continue his interests in fetal growth, publishing a paper in 1970 with the then late Professor Huggett. He continued his early interest in amphibians and reptiles into retirement particularly in Kent.

I knew both Bellairs and Frazer but only when writing this did I realise that Frazer was the older man.

Smith and Frazer from Contributions to the History of Herpetology (see below); Bellairs from Herpetological Journal


It was not unusual, of course, for those in medical practice to indulge in biological hobbies but the involvement of the the three authors was something on a much greater scale. Britain’s medical schools, which I have to explain were and are very different from those, say, in the U.S.A., produced many qualified doctors who did not want to become doctors in the first place but persisted under parental pressure, were attracted to biological research but who finished their clinical studies in order to gain a qualification, or who simply found they did not like medical practice once they had qualified. Direct entry into the biological sciences was often difficult especially for boys since biology was not taught at all in what were considered the good schools.

An example from our time as students in the 1960s was the famous insect physiologist, Sir Vincent Wigglesworth FRS (1899-1994). All his spare time as a medical student was spent studying insects. Medical graduates turning to zoology were always described as ‘having seen the light’.

Biographies of all three are in the three volumes of Contributions to the History of Herpetology,  edited by Kraig Adler, Society for the Study of Reptiles and Amphibians.

Frazer D. 1983. Reptiles and Amphibians in Britain. London: Collins

Smith M. 1951. The British Amphibians and Reptiles. London: Collins